Systems and methods for endometrial ablation

ABSTRACT

A system for treating uterine tissue having a seal assembly configured for positioning in a patient&#39;s cervical canal and uterine cavity; an expandable distal balloon portion; an expandable elongate medial balloon portion configured for movement between a first transversely expanded shape for engaging a cervical canal and a second transversely non-expanded shape for trans-cervical insertion; and a fluid source in communication with distal balloon portion and medial balloon portion for expansion of said balloon portions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Application No.61/393,776 (Attorney Docket No. 37646-713.101; 027962-001300US), filedon Oct. 15, 2010, the full disclosure of which is incorporated herein byreference.

This application is related to but does not claim priority fromapplication Ser. Nos. 12/711,506 , (Attorney Docket No. 37646-708.201;027962-000800US), filed on Feb. 24, 2010, and Ser. No. 13/094,715(Attorney Docket No. 37646-711.201; 027962-001110US), filed on Apr. 26,2011, the full disclosures of which are incorporated herein byreference.

BACKGROUND

1. Field of the Invention

The present invention relates to electrosurgical methods and devices forglobal endometrial ablation in a treatment of menorrhagia. Moreparticularly, the present invention relates to applying radiofrequencycurrent to endometrial tissue by means of capacitively coupling thecurrent through an expandable, thin-walled dielectric member enclosingan ionized gas.

A variety of devices have been developed or proposed for endometrialablation. Of relevance to the present invention, a variety ofradiofrequency ablation devices have been proposed including solidelectrodes, balloon electrodes, metalized fabric electrodes, and thelike. While often effective, many of the prior electrode designs havesuffered from one or more deficiencies, such as relatively slowtreatment times, incomplete treatments, non-uniform ablation depths, andrisk of injury to adjacent organs.

For these reasons, it would be desirable to provide systems and methodsthat allow for endometrial ablation using radiofrequency current whichis rapid, provides for controlled ablation depth and which reduce therisk of injury to adjacent organs. At least some of these objectiveswill be met by the invention described herein.

2. Description of the Background Art.

U.S. Pat. Nos. 5,540,658 and 5,653,692 describe intrauterine ablationdevices with cervical seals. U.S. Pat. Nos. 5,769,880; 6,296,639;6,663,626; and 6,813,520 describe intrauterine ablation devices formedfrom a permeable mesh defining electrodes for the application ofradiofrequency energy to ablate uterine tissue. U.S. Pat. No. 4,979,948describes a balloon filled with an electrolyte solution for applyingradiofrequency current to a mucosal layer via capacitive coupling. US2008/097425, having common inventorship with the present application,describes delivering a pressurized flow of a liquid medium which carriesa radiofrequency current to tissue, where the liquid is ignited into aplasma as it passes through flow orifices. U.S. Pat. No. 5,891,134describes a radiofrequency heater within an enclosed balloon. U.S. Pat.No. 6,041,260 describes radiofrequency electrodes distributed over theexterior surface of a balloon which is inflated in a body cavity to betreated. U.S. Pat. No. 7,371,231 and US 2009/054892 describe aconductive balloon having an exterior surface which acts as an electrodefor performing endometrial ablation. U.S. Pat. No. 5,191,883 describesbipolar heating of a medium within a balloon for thermal ablation. U.S.Pat. No. 6,736,811 and U.S. Pat. No. 5,925,038 show an inflatableconductive electrode.

BRIEF SUMMARY OF THE INVENTION

The present invention provides methods, systems and devices for sealingof the cervix or cervical canal, for example as part of a uterineaccess, ablation, or other therapeutic or diagnostic procedure. Themethods and systems may also provide for evaluation of the integrity ofa uterine cavity. The uterine cavity may be perforated or otherwisedamaged by the transcervical introduction of probes and instruments intothe uterine cavity. If the uterine wall is perforated, it would bepreferable to defer any ablation treatment until the uterine wall ishealed.

Embodiments herein provide a system for treating uterine tissue,comprising an expandable RF energy delivery surface for positioning in auterine cavity; an RF source configured to deliver current across thesurface; and a sealing structure disposed adjacent the energy deliverysurface and configured for positioning in and sealing a cervical canal.

The sealing structure may be, for example, an elongated bellows-likemember with a compliant wall. In embodiments, the sealing structure hasa longitudinal axis, and has a repose state with a plurality of annularridges for engaging tissue surrounding a cervical canal. The sealingstructure can be axially stretched to provide a reduced cross sectionfor insertion in the patient's uterine canal.

In further embodiments, the sealing structure is elongated with a distalportion having a greater cross section in a repose state, and a proximalportion with a lesser cross section in a repose state.

The sealing structure may be carried concentrically around a distalportion of a sleeve assembly or support member that carries the RFenergy delivery surface of the endometrial ablation system.

In embodiments, the energy delivery surface comprises a wall surroundingan interior chamber. The wall may include at least partly a dielectric.The wall may further include an electrode. The interior chamber may befluid-tight.

In accordance with still further embodiments, a method of treatinguterine tissue is provided, comprising expanding a RF energy deliverysurface within a patient's uterine cavity; expanding an expandablemember in the patient's cervical canal; and activating an RF sourceconfigured to deliver current across the surface to ablate endometrialtissue.

In further embodiments, expanding the RF energy delivery surfacecomprises expanding a frame supporting the surface.

Systems according to the present invention for transcervicalintroduction to a patient's uterus comprise a radially expanding sleeveand a probe shaft. The radially expanding sleeve has a proximal end, adistal end, and a central passage between said ends. The sleeve isadapted to be introduced into the cervix or cervical canal in a reducedwidth configuration and to be immobilized within the cervical canal inan expanded width configuration. The probe shaft is slideably receivedin the central passage of the sleeve so that the shaft may be advanced,retracted, and otherwise manipulated within the central passage whilethe sleeve remains immobilized in the cervix or cervical canal,typically during a therapeutic or diagnostic procedure, more typicallyduring a uterine ablation procedure. Such sealing of the cervix and/orcervical canal can inhibit and preferably prevent thermal or otherdamage from occurring during the procedure. Sealing the cervix and/orcervical canal with a sleeve that can remain immobilized during theprocedure is particularly advantageous since it allows the therapeutic,diagnostic, or other device associated with the probe shaft to berepositioned and otherwise manipulated during the procedure whileminimizing the risk of disturbing the protective seal. While priordevices have had seals affixed to the therapeutic device, such fixedseals are more likely to be dislodged during performance of thetherapeutic and/or diagnostic procedure.

In specific embodiments of the systems of the present invention, thesleeve includes a proximal collar with a locking mechanism which canselectively lock and unlock the sleeve to the probe shaft. With such alocking mechanism, the physician is able to optimally position the probeand at least temporarily lock the probe relative to the sleeve toinhibit subsequent dislodgement or movement of the probe duringremaining portions or segments of the protocol. For example, whenperforming uterine ablation procedures, it may desirable to immobilizethe sleeve in the cervix, position a thermal or other treatment elementon the probe shaft within the uterus (while the sleeve remainsimmobilized), lock the probe shaft to the sleeve once the thermalablation element has been properly positioned, and then perform thermalablation while the thermal ablation element remains stabilized in theappropriate position by its attachment to the sleeve which isimmobilized in the cervix. Locking mechanism may comprise any suitablelatch, lock, anchor, or other device which can be selectively engaged tofix the probe to the sleeve and then selectively disengaged to releasethe probe so that it can again be moved relative to the sleeve.

In further specific examples, the sleeve may comprise a variety ofspecific features which enable it to be preferentially locked within thecervix or cervical canal. For example, the sleeve may comprise a distalballoon which can be inflated to engage an interior surface of theuterus or a posterior surface of the cervical os, where the balloon maybe part of or separate from a mechanism or segment which locks thesleeve within the cervical canal itself. The sleeve may, for example,comprise a tubular assembly having a deformable thin-walled sealdisposed over the tubular assembly, where the seal is configured foraxial deformation between a first transversally expanded shaped forengaging the cervical canal and a second transversally non-expandedshape which permits the sleeve to be transcervically inserted andsubsequently removed. Usually, the proximal and distal ends of the sealwill be coupled to the tubular assembly, more typically being coupled tofirst and second concentric tubes which form the tubular assembly, whererelative axial movement of the concentric sleeves provides the desiredaxial deformation of the sleeve (e.g., axially extending or opening thetubes will axially lengthen the sleeve and reduce the sleeve's width. Insuch embodiments, the sleeve typically comprises an elastomericmaterial, such as a thin walled silicone elastomer, optionally havinghelical ridges and valley regions which form upon axial shortening. Inaddition to deforming the sleeve in response to axial extension andcompression, the systems may further comprise a pressurized fluid sourcewhich is connected to the tubular assembly to selectively inflate thedeformable thin-walled seal when the seal is already in itstransversally expanded shape. In such inflatable embodiments, thedeformable thin-walled seal will have annular or helical first andsecond regions having first and second durometers, respectively, withthe region having a higher durometer than the second region. Thepressurized fluid from the source will be connected to apply to the sealto expand the second region but not the first region, as controlled byrespective durometers of the regions. In a specific embodiment, thedeformable thin-walled seal has a stretched (low profile or width)cross-section for transcervical insertion and a non-stretched (expandedwidth) cross-section for sealing the cervical canal. In theseembodiments, the seal contains a fluid-tight interior chamber having awall with annular or helical regions configured for differentialtransverse expansion upon inflation. The embodiments will also have apressurized fluid source communicating with the interior chamber, wherefluid from the pressurized fluid source differentially inflates the sealto expand the annular or helical regions while the valleys between theridges may be reinforced or otherwise inhibited from radially expanding.

The present invention further provides methods for accessing a patient'suterus. The methods comprise immobilizing a sleeve in the patient'scervix or cervical canal where the sleeve has a central passage. A probeshaft is repositioned within the central passage while the sleeveremains immobilized, thus allowing the physician to position orreposition a diagnostic or therapeutic tool on the shaft within theuterus while minimizing the risk of disrupting the seal to the cervix.The sleeve may be initially introduced to the cervical canal while theprobe is present in the central passage or, alternatively, the sleevemay be positioned without the sleeve being present. In the latter case,the sleeve will be advanced through the probe after the seal has beenimmobilized. Both cases, the sleeve is typically immobilized by radiallyexpanding a wall or exterior portion of the sleeve within the cervicalcanal. Expansion of the sleeve may be achieved by causing or allowingthe sleeve to axially foreshorten and/or by inflating at least a portionof the wall of the sleeve. Optionally, distal balloon may be inflated orotherwise expanded within the uterine cavity at the distal end of thesleeve. Optionally, the sleeve and the probe shaft may be selectivelylocked to each other this so that the immobilized sleeve may stabilizethe position of a therapeutic or a diagnostic tool on the probe shaftwithin the uterus. Typically, locking is accomplished by actuating alocking mechanism on the sleeve, usually on a proximal collar of thesleeve which remains accessible to the treating physician during theprocedure.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the invention and to see how it may becarried out in practice, some preferred embodiments are next described,by way of non-limiting examples only, with reference to the accompanyingdrawings, in which like reference characters denote correspondingfeatures consistently throughout similar embodiments in the attacheddrawings.

FIG. 1 is a perspective view of an ablation system corresponding to theinvention, including a hand-held electrosurgical device for endometrialablation, RF power source, gas source and controller.

FIG. 2 is a view of the hand-held electrosurgical device of FIG. 1 witha deployed, expanded thin-walled dielectric structure.

FIG. 3 is a block diagram of components of one electrosurgical systemcorresponding to the invention.

FIG. 4 s a block diagram of the gas flow components of theelectrosurgical system of FIG. 1.

FIG. 5 is an enlarged perspective view of the expanded thin-walleddielectric structure, showing an expandable-collapsible frame with thethin dielectric wall in phantom view.

FIG. 6 is a partial sectional view of the expanded thin-walleddielectric structure of FIG. 5 showing (i) translatable members of theexpandable-collapsible frame a that move the structure between collapsedand (ii) gas inflow and outflow lumens.

FIG. 7 is a sectional view of an introducer sleeve showing variouslumens of the introducer sleeve taken along line 7-7 of FIG. 6.

FIG. 8A is an enlarged schematic view of an aspect of a method of theinvention illustrating the step introducing an introducer sleeve into apatient's uterus.

FIG. 8B is a schematic view of a subsequent step of retracting theintroducer sleeve to expose a collapsed thin-walled dielectric structureand internal frame in the uterine cavity.

FIG. 8C is a schematic view of subsequent steps of the method,including, (i) actuating the internal frame to move the a collapsedthin-walled dielectric structure to an expanded configuration, (ii)inflating a cervical-sealing balloon carried on the introducer sleeve,and (iii) actuating gas flows and applying RF energy tocontemporaneously ionize the gas in the interior chamber and causecapacitive coupling of current through the thin-walled dielectricstructure to cause ohmic heating in the engaged tissue indicated bycurrent flow paths.

FIG. 8D is a schematic view of a subsequent steps of the method,including: (i) advancing the introducer sleeve over the thin-walleddielectric structure to collapse it into an interior bore shown inphantom view, and (ii) withdrawing the introducer sleeve and dielectricstructure from the uterine cavity.

FIG. 9 is a cut-away perspective view of an alternative expandedthin-walled dielectric structure similar to that of FIGS. 5 and 6 showan alternative electrode configuration.

FIG. 10 is an enlarged cut-away view of a portion of the expandedthin-walled dielectric structure of FIG. 9 showing the electrodeconfiguration.

FIG. 11 is a diagram of a radiofrequency energy delivery apparatus andmethod corresponding to the invention.

FIG. 12 is a schematic view of the working end of the ablation device ofFIGS. 1-2 depicting three outlines of the expandable working end in arange of slightly-expanded to fully-expanded positions.

FIG. 13A is a schematic representation of an indicator mechanism in thehandle of the ablation device of FIGS. 1-2 for indicating a first degreeof expansion of the dielectric structure in a range shown in FIG. 12.

FIG. 13B is a schematic representation of the indicator mechanism ofFIG. 13A indicating a second the degree of expansion of the dielectricstructure.

FIG. 14 is a perspective view of an alternative working end of anendometrial ablation system with an elongated, elastomeric bellows-likeseal for sealing the patient's cervical canal.

FIG. 15A is a cut-away view of the cervical seal of FIG. 14 in a reposeshape.

FIG. 15B is a cut-away view of the cervical seal of FIGS. 14 and 15A ina stretched, tensioned shape.

FIG. 16A is a schematic view of a method of the invention illustratingthe step introducing an introducer sleeve with the seal of FIG. 14 intoa patient's uterus.

FIG. 16B is a schematic view of a subsequent step of deploying the sealof FIG. 14 in the patient's cervical canal.

FIG. 17 is a side view of another embodiment of an elongated,elastomeric bellows-like seal for sealing the patient's cervical canal.

FIG. 18 is a side view of another embodiment of an elongated,elastomeric bellows-like seal for sealing the patient's cervical canal.

FIG. 19 is a side view of another embodiment of an elongated,elastomeric bellows-like seal for sealing the patient's cervical canal.

FIG. 20 is a side view of another embodiment of an elongated,elastomeric bellows-like seal for sealing the patient's cervical canal.

FIG. 21 is a side view of another embodiment of an elongated sealassembly for sealing the patient's cervical canal in an endometrialablation procedure.

FIG. 22A is a schematic view of an initial step of deploying the sealassembly of FIG. 21 in the patient's cervical canal, with the expandableportions of the seal in collapsed positions.

FIG. 22B is a schematic view of subsequent steps of deploying the sealassembly, wherein an inflation source is actuated to expand theexpandable portions of the seal to seal the uterine cavity.

DETAILED DESCRIPTION

In general, an electrosurgical ablation system is described herein thatcomprises an elongated introducer member for accessing a patient'suterine cavity with a working end that deploys an expandable thin-walleddielectric structure containing an electrically non-conductive gas as adielectric. In one embodiment, an interior chamber of the thin-walleddielectric structure contains a circulating neutral gas such as argon.An RF power source provides current that is coupled to the neutral gasflow by a first polarity electrode disposed within the interior chamberand a second polarity electrode at an exterior of the working end. Thegas flow, which is converted to a conductive plasma by an electrodearrangement, functions as a switching mechanism that permits currentflow to engaged endometrial tissue only when the voltage across thecombination of the gas, the thin-walled dielectric structure and theengaged tissue reaches a threshold that causes capacitive couplingacross the thin-walled dielectric material. By capacitively couplingcurrent to tissue in this manner, the system provides a substantiallyuniform tissue effect within all tissue in contact with the expandeddielectric structure. Further, the invention allows the neutral gas tobe created contemporaneously with the capacitive coupling of current totissue.

In general, this disclosure may use the terms “plasma,” “conductive gas”and “ionized gas” interchangeably. A plasma consists of a state ofmatter in which electrons in a neutral gas are stripped or “ionized”from their molecules or atoms. Such plasmas can be formed by applicationof an electric field or by high temperatures. In a neutral gas,electrical conductivity is non-existent or very low. Neutral gases actas a dielectric or insulator until the electric field reaches abreakdown value, freeing the electrons from the atoms in an avalancheprocess thus forming a plasma. Such a plasma provides mobile electronsand positive ions, and acts as a conductor which supports electriccurrents and can form spark or arc. Due to their lower mass, theelectrons in a plasma accelerate more quickly in response to an electricfield than the heavier positive ions, and hence carry the bulk of thecurrent.

FIG. 1 depicts one embodiment of an electrosurgical ablation system 100configured for endometrial ablation. The system 100 includes a hand-heldapparatus 105 with a proximal handle 106 shaped for grasping with ahuman hand that is coupled to an elongated introducer sleeve 110 havingaxis 111 that extends to a distal end 112. The introducer sleeve 110 canbe fabricated of a thin-walled plastic, composite, ceramic or metal in around or oval cross-section having a diameter or major axis ranging fromabout 4 mm to 8 mm in at least a distal portion of the sleeve thataccesses the uterine cavity. The handle 106 is fabricated of anelectrically insulative material such as a molded plastic with apistol-grip having first and second portions, 114 a and 114 b, that canbe squeezed toward one another to translate an elongated translatablesleeve 115 which is housed in a bore 120 in the elongated introducersleeve 110. By actuating the first and second handle portions, 114 a and114 b, a working end 122 can be deployed from a first retracted position(FIG. 1) in the distal portion of bore 120 in introducer sleeve 110 toan extended position as shown in FIG. 2. In FIG. 2, it can be seen thatthe first and second handle portions, 114 a and 114 b, are in a secondactuated position with the working end 122 deployed from the bore 120 inintroducer sleeve 110.

FIGS. 2 and 3 shows that ablation system 100 includes an RF energysource 130A and RF controller 130B in a control unit 135. The RF energysource 130A is connected to the hand-held device 105 by a flexibleconduit 136 with a plug-in connector 137 configured with a gas inflowchannel, a gas outflow channel, and first and second electrical leadsfor connecting to receiving connector 138 in the control unit 135. Thecontrol unit 135, as will be described further below in FIGS. 3 and 4,further comprises a neutral gas inflow source 140A, gas flow controller140B and optional vacuum or negative pressure source 145 to providecontrolled gas inflows and gas outflows to and from the working end 122.The control unit 135 further includes a balloon inflation source 148 forinflating an expandable sealing balloon 225 carried on introducer sleeve110 as described further below.

Referring to FIG. 2, the working end 122 includes a flexible,thin-walled member or structure 150 of a dielectric material that whenexpanded has a triangular shape configured for contacting the patient'sendometrial lining that is targeted for ablation. In one embodiment asshown in FIGS. 2, 5 and 6, the dielectric structure 150 comprises athin-walled material such as silicone with a fluid-tight interiorchamber 152.

In an embodiment, an expandable-collapsible frame assembly 155 isdisposed in the interior chamber. Alternatively, the dielectricstructure may be expanded by a neutral gas without a frame, but using aframe offers a number of advantages. First, the uterine cavity isflattened with the opposing walls in contact with one another. Expandinga balloon-type member may cause undesirable pain or spasms. For thisreason, a flat structure that is expanded by a frame is better suitedfor deployment in the uterine cavity. Second, in embodiments herein, theneutral gas is converted to a conductive plasma at a very low pressurecontrolled by gas inflows and gas outflows--so that any pressurizationof a balloon-type member with the neutral gas may exceed a desiredpressure range and would require complex controls of gas inflows and gasoutflows. Third, as described below, the frame provides an electrode forcontact with the neutral gas in the interior chamber 152 of thedielectric structure 150, and the frame 155 extends into all regions ofthe interior chamber to insure electrode exposure to all regions of theneutral gas and plasma. The frame 155 can be constructed of any flexiblematerial with at least portions of the frame functioning as springelements to move the thin-walled structure 150 from a collapsedconfiguration (FIG. 1) to an expanded, deployed configuration (FIG. 2)in a patient's uterine cavity. In one embodiment, the frame 155comprises stainless steel elements 158 a, 158 b and 160 a and 160 b thatfunction akin to leaf springs. The frame can be a stainless steel suchas 316 SS, 17A SS, 420 SS, 440 SS or the frame can be a NiTi material.The frame preferably extends along a single plane, yet remains thintransverse to the plane, so that the frame may expand into the uterinecavity. The frame elements can have a thickness ranging from about0.005″ to 0.025″. As can be seen in FIGS. 5 and 6, the proximal ends 162a and 162 b of spring elements 158 a, 158 b are fixed (e.g., by welds164) to the distal end 165 of sleeve member 115. The proximal ends 166 aand 166 b of spring elements 160 a, 160 b are welded to distal portion168 of a secondary translatable sleeve 170 that can be extended frombore 175 in translatable sleeve 115. The secondary translatable sleeve170 is dimensioned for a loose fit in bore 175 to allow gas flows withinbore 175. FIGS. 5 and 6 further illustrate the distal ends 176 a and 176b of spring elements 158 a, 158 b are welded to distal ends 178 a and178 b of spring elements 160 a and 160 b to thus provide a frame 155that can be moved from a linear shape (see FIG.1) to an expandedtriangular shape (FIGS. 5 and 6).

As will be described further below, the bore 175 in sleeve 115 and bore180 in secondary translatable sleeve 170 function as gas outflow and gasinflow lumens, respectively. It should be appreciated that the gasinflow lumen can comprise any single lumen or plurality of lumens ineither sleeve 115 or sleeve 170 or another sleeve, or other parts of theframe 155 or the at least one gas flow lumen can be formed into a wallof dielectric structure 150. In FIGS. 5, 6 and 7 it can be seen that gasinflows are provided through bore 180 in sleeve 170, and gas outflowsare provided in bore 175 of sleeve 115. However, the inflows andoutflows can be also be reversed between bores 175 and 180 of thevarious sleeves. FIGS. 5 and 6 further show that a rounded bumperelement 185 is provided at the distal end of sleeve 170 to insure thatno sharp edges of the distal end of sleeve 170 can contact the inside ofthe thin dielectric wall 150. In one embodiment, the bumper element 185is silicone, but it could also comprise a rounded metal element. FIGS. 5and 6 also show that a plurality of gas inflow ports 188 can be providedalong a length of in sleeve 170 in chamber 152, as well as a port 190 inthe distal end of sleeve 170 and bumper element 185. The sectional viewof FIG. 7 also shows the gas flow passageways within the interior ofintroducer sleeve 110.

It can be understood from FIGS. 1, 2, 5 and 6 that actuation of firstand second handle portions, 114 a and 114 b, (i) initially causesmovement of the assembly of sleeves 115 and 170 relative to bore 120 ofintroducer sleeve 110, and (ii) secondarily causes extension of sleeve170 from bore 175 in sleeve 115 to expand the frame 155 into thetriangular shape of FIG. 5. The dimensions of the triangular shape aresuited for a patient uterine cavity, and for example can have an axiallength A ranging from 4 to 10 cm and a maximum width B at the distal endranging from about 2 to 5 cm. In one embodiment, the thickness C of thethin-walled structure 150 can be from 1 to 4 mm as determined by thedimensions of spring elements 158 a, 158 b, 160 a and 160 b of frameassembly 155. It should be appreciated that the frame assembly 155 cancomprise round wire elements, flat spring elements, of any suitablemetal or polymer that can provide opening forces to move thin-walledstructure 150 from a collapsed configuration to an expandedconfiguration within the patient uterus. Alternatively, some elements ofthe frame 155 can be spring elements and some elements can be flexiblewithout inherent spring characteristics.

As will be described below, the working end embodiment of FIGS. 2, 5 and6 has a thin-walled structure 150 that is formed of a dielectricmaterial such as silicone that permits capacitive coupling of current toengaged tissue while the frame assembly 155 provides structural supportto position the thin-walled structure 150 against tissue. Further, gasinflows into the interior chamber 152 of the thin-walled structure canassist in supporting the dielectric wall so as to contact endometrialtissue. The dielectric thin-walled structure 150 can be free fromfixation to the frame assembly 155, or can be bonded to anoutward-facing portion or portions of frame elements 158 a and 158 b.The proximal end 182 of thin-walled structure 150 is bonded to theexterior of the distal end of sleeve 115 to thus provide a sealed,fluid-tight interior chamber 152 (FIG. 5).

In one embodiment, the gas inflow source 140A comprises one or morecompressed gas cartridges that communicate with flexible conduit 136through plug-in connector 137 and receiving connector 138 in the controlunit 135 (FIGS. 1-2). As can be seen in FIGS. 5-6, the gas inflows fromsource 140A flow through bore 180 in sleeve 170 to open terminations 188and 190 therein to flow into interior chamber 152. A vacuum source 145is connected through conduit 136 and connector 137 to allow circulationof gas flow through the interior chamber 152 of the thin-walleddielectric structure 150. In FIGS. 5 and 6, it can be seen that gasoutflows communicate with vacuum source 145 through open end 200 of bore175 in sleeve 115. Referring to FIG. 5, it can be seen that frameelements 158 a and 158 b are configured with a plurality of apertures202 to allow for gas flows through all interior portions of the frameelements, and thus gas inflows from open terminations 188, 190 in bore180 are free to circulated through interior chamber 152 to return to anoutflow path through open end 200 of bore 175 of sleeve 115. As will bedescribed below (see FIGS. 3-4), the gas inflow source 140A is connectedto a gas flow or circulation controller 140B which controls a pressureregulator 205 and also controls vacuum source 145 which is adapted forassisting in circulation of the gas. It should be appreciated that theframe elements can be configured with apertures, notched edges or anyother configurations that allow for effective circulation of a gasthrough interior chamber 152 of the thin-walled structure 150 betweenthe inflow and outflow passageways.

Now turning to the electrosurgical aspects of the invention, FIGS. 5 and6 illustrate opposing polarity electrodes of the system 100 that areconfigured to convert a flow of neutral gas in chamber 152 into a plasma208 (FIG. 6) and to allow capacitive coupling of current through a wall210 of the thin-walled dielectric structure 150 to endometrial tissue incontact with the wall 210. The electrosurgical methods of capacitivelycoupling RF current across a plasma 208 and dielectric wall 210 aredescribed in U.S. patent application Ser. No. 12/541,043; filed Aug. 13,2009 (Atty. Docket No. 027980-000110US) and U.S. application Ser. No.12/541,050 (Atty. Docket No. 027980-000120US), referenced above. InFIGS. 5 and 6, the first polarity electrode 215 is within interiorchamber 152 to contact the neutral gas flow and comprises the frameassembly 155 that is fabricated of an electrically conductive stainlesssteel. In another embodiment, the first polarity electrode can be anyelement disposed within the interior chamber 152, or extendable intointerior chamber 152. The first polarity electrode 215 is electricallycoupled to sleeves 115 and 170 which extends through the introducersleeve 110 to handle 106 and conduit 136 and is connected to a firstpole of the RF source energy source 130A and controller 130B. A secondpolarity electrode 220 is external of the internal chamber 152 and inone embodiment the electrode is spaced apart from wall 210 of thethin-walled dielectric structure 150. In one embodiment as depicted inFIGS. 5 and 6, the second polarity electrode 220 comprises a surfaceelement of an expandable balloon member 225 carried by introducer sleeve110. The second polarity electrode 220 is coupled by a lead (not shown)that extends through the introducer sleeve 110 and conduit 136 to asecond pole of the RF source 130A. It should be appreciated that secondpolarity electrode 220 can be positioned on sleeve 110 or can beattached to surface portions of the expandable thin-walled dielectricstructure 150, as will be described below, to provide suitable contactwith body tissue to allow the electrosurgical ablation of the method ofthe invention. The second polarity electrode 220 can comprise a thinconductive metallic film, thin metal wires, a conductive flexiblepolymer or a polymeric positive temperature coefficient material. In oneembodiment depicted in FIGS. 5 and 6, the expandable member 225comprises a thin-walled compliant balloon having a length of about 1 cmto 6 cm that can be expanded to seal the cervical canal. The balloon 225can be inflated with a gas or liquid by any inflation source 148, andcan comprise a syringe mechanism controlled manually or by control unit135. The balloon inflation source 148 is in fluid communication with aninflation lumen 228 in introducer sleeve 110 that extends to aninflation chamber of balloon 225 (see FIG. 7).

Referring back to FIG. 1, the control unit 135 can include a display 230and touch screen or other controls 232 for setting and controllingoperational parameters such as treatment time intervals, treatmentalgorithms, gas flows, power levels and the like. Suitable gases for usein the system include argon, other noble gases and mixtures thereof. Inone embodiment, a footswitch 235 is coupled to the control unit 135 foractuating the system.

The box diagrams of FIGS. 3 and 4 schematically depict the system 100,subsystems and components that are configured for an endometrialablation system. In the box diagram of FIG. 3, it can be seen that RFenergy source 130A and circuitry is controlled by a controller 130B. Thesystem can include feedback control systems that include signalsrelating to operating parameters of the plasma in interior chamber 152of the dielectric structure 150. For example, feedback signals can beprovided from at least one temperature sensor 240 in the interiorchamber 152 of the dielectric structure 150, from a pressure sensorwithin, or in communication, with interior chamber 152, and/or from agas flow rate sensor in an inflow or outflow channel of the system. FIG.4 is a schematic block diagram of the flow control components relatingto the flow of gas media through the system 100 and hand-held device105. It can be seen that a pressurized gas source 140A is linked to adownstream pressure regulator 205, an inflow proportional valve 246,flow meter 248 and normally closed solenoid valve 250. The valve 250 isactuated by the system operator which then allows a flow of a neutralgas from gas source 140A to circulate through flexible conduit 136 andthe device 105. The gas outflow side of the system includes a normallyopen solenoid valve 260, outflow proportional valve 262 and flow meter264 that communicate with vacuum pump or source 145. The gas can beexhausted into the environment or into a containment system. Atemperature sensor 270 (e.g., thermocouple) is shown in FIG. 4 that isconfigured for monitoring the temperature of outflow gases. FIG. 4further depicts an optional subsystem 275 which comprises a vacuumsource 280 and solenoid valve 285 coupled to the controller 140B forsuctioning steam from a uterine cavity 302 at an exterior of thedielectric structure 150 during a treatment interval. As can beunderstood from FIG. 4, the flow passageway from the uterine cavity 302can be through bore 120 in sleeve 110 (see FIGS. 2, 6 and 7) or anotherlumen in a wall of sleeve 110 can be provided.

FIGS. 8A-8D schematically illustrate a method of the invention wherein(i) the thin-walled dielectric structure 150 is deployed within apatient uterus and (ii) RF current is applied to a contained neutral gasvolume in the interior chamber 152 to contemporaneously create a plasma208 in the chamber and capacitively couple current through the thindielectric wall 210 to apply ablative energy to the endometrial liningto accomplish global endometrial ablation.

More in particular, FIG. 8A illustrates a patient uterus 300 withuterine cavity 302 surrounded by endometrium 306 and myometrium 310. Theexternal cervical os 312 is the opening of the cervix 314 into thevagina 316. The internal os or opening 320 is a region of the cervicalcanal that opens to the uterine cavity 302. FIG. 8A depicts a first stepof a method of the invention wherein the physician has introduced adistal portion of sleeve 110 into the uterine cavity 302. The physiciangently can advance the sleeve 110 until its distal tip contacts thefundus 324 of the uterus. Prior to insertion of the device, thephysician can optionally introduce a sounding instrument into theuterine cavity to determine uterine dimensions, for example from theinternal os 320 to fundus 324.

FIG. 8B illustrates a subsequent step of a method of the inventionwherein the physician begins to actuate the first and second handleportions, 114 a and 114 b, and the introducer sleeve 110 retracts in theproximal direction to expose the collapsed frame 155 and thin-walledstructure 150 within the uterine cavity 302. The sleeve 110 can beretracted to expose a selected axial length of thin-walled dielectricstructure 150, which can be determined by markings 330 on sleeve 115(see FIG. 1) which indicate the axial travel of sleeve 115 relative tosleeve 170 and thus directly related to the length of deployedthin-walled structure 150. FIG. 2 depicts the handle portions 114 a and114 b fully approximated thus deploying the thin-walled structure to itsmaximum length.

In FIG. 8B, it can be understood that the spring frame elements 158 a,158 b, 160 a and 160 b move the dielectric structure 150 from anon-expanded position to an expanded position in the uterine cavity asdepicted by the profiles in dashed lines. The spring force of the frame155 will expand the dielectric structure 150 until limited by thedimensions of the uterine cavity.

FIG. 8C illustrates several subsequent steps of a method of theinvention. FIG. 8C first depicts the physician continuing to actuate thefirst and second handle portions, 114 a and 114 b, which furtheractuates the frame 155 (see FIGS. 5-6) to expand the frame 155 andthin-walled structure 150 to a deployed triangular shape to contact thepatient's endometrial lining 306. The physician can slightly rotate andmove the expanding dielectric structure 150 back and forth as thestructure is opened to insure it is opened to the desired extent. Inperforming this step, the physician can actuate handle portions, 114 aand 114 b, a selected degree which causes a select length of travel ofsleeve 170 relative to sleeve 115 which in turn opens the frame 155 to aselected degree. The selected actuation of sleeve 170 relative to sleeve115 also controls the length of dielectric structure deployed fromsleeve 110 into the uterine cavity. Thus, the thin-walled structure 150can be deployed in the uterine cavity with a selected length, and thespring force of the elements of frame 155 will open the structure 150 toa selected triangular shape to contact or engage the endometrium 306. Inone embodiment, the expandable thin-walled structure 150 is urged towardand maintained in an open position by the spring force of elements ofthe frame 155. In the embodiment depicted in FIGS. 1 and 2, the handle106 includes a locking mechanism with finger-actuated sliders 332 oneither side of the handle that engage a grip-lock element against anotch in housing 333 coupled to introducer sleeve 110 (FIG. 2) to locksleeves 115 and 170 relative to introducer sleeve 110 to maintain thethin-walled dielectric structure 150 in the selected open position.

FIG. 8C further illustrates the physician expanding the expandableballoon structure 225 from inflation source 148 to thus provide anelongated sealing member to seal the cervix 314 outward from theinternal os 320. Following deployment of the thin-walled structure 150and balloon 225 in the cervix 314, the system 100 is ready for theapplication of RF energy to ablate endometrial tissue 306. FIG. 8C nextdepicts the actuation of the system 100, for example, by actuatingfootswitch 235, which commences a flow of neutral gas from source 140Ainto the interior chamber 152 of the thin-walled dielectric structure150. Contemporaneous with, or after a selected delay, the system'sactuation delivers RF energy to the electrode arrangement which includesfirst polarity electrode 215 (+) of frame 155 and the second polarityelectrode 220 (−) which is carried on the surface of expandable balloonmember 225. The delivery of RF energy delivery will instantly convertthe neutral gas in interior chamber 152 into conductive plasma 208 whichin turn results in capacitive coupling of current through the dielectricwall 210 of the thin-walled structure 150 resulting in ohmic heating ofthe engaged tissue. FIG. 8C schematically illustrates the multiplicityof RF current paths 350 between the plasma 208 and the second polarityelectrode 220 through the dielectric wall 210. By this method, it hasbeen found that ablation depths of three mm to six mm or more can beaccomplished very rapidly, for example in 60 seconds to 120 secondsdependent upon the selected voltage and other operating parameters. Inoperation, the voltage at which the neutral gas inflow, such as argon,becomes conductive (i.e., converted in part into a plasma) is dependentupon a number of factors controlled by the controllers 130B and 140B,including the pressure of the neutral gas, the volume of interiorchamber 152, the flow rate of the gas through the chamber 152, thedistance between electrode 210 and interior surfaces of the dielectricwall 210, the dielectric constant of the dielectric wall 210 and theselected voltage applied by the RF source 130, all of which can beoptimized by experimentation. In one embodiment, the gas flow rate canbe in the range of 5 ml/sec to 50 ml/sec. The dielectric wall 210 cancomprise a silicone material having a thickness ranging from a 0.005″ to0.015 and having a relative permittivity in the range of 3 to 4. The gascan be argon supplied in a pressurized cartridge which is commerciallyavailable. Pressure in the interior chamber 152 of dielectric structure150 can be maintained between 14 psia and 15 psia with zero or negativedifferential pressure between gas inflow source 140A and negativepressure or vacuum source 145. The controller is configured to maintainthe pressure in interior chamber in a range that varies by less than 10%or less than 5% from a target pressure. The RF power source 130A canhave a frequency of 450 to 550 KHz, and electrical power can be providedwithin the range of 600 Vrms to about 1200 Vrms and about 0.2 Amps to0.4 Amps and an effective power of 40 W to 100 W. In one method, thecontrol unit 135 can be programmed to delivery RF energy for apreselected time interval, for example, between 60 seconds and 120seconds. One aspect of a treatment method corresponding to the inventionconsists of ablating endometrial tissue with RF energy to elevateendometrial tissue to a temperature greater than 45 degrees Celsius fora time interval sufficient to ablate tissue to a depth of at least 1 mm.Another aspect of the method of endometrial ablation of consists ofapplying radiofrequency energy to elevate endometrial tissue to atemperature greater than 45 degrees Celsius without damaging themyometrium.

FIG. 8D illustrates a final step of the method wherein the physiciandeflates the expandable balloon member 225 and then extends sleeve 110distally by actuating the handles 114 a and 114 b to collapse frame 155and then retracting the assembly from the uterine cavity 302.Alternatively, the deployed working end 122 as shown in FIG. 8C can bewithdrawn in the proximal direction from the uterine cavity wherein theframe 155 and thin-walled structure 150 will collapse as it is pulledthrough the cervix. FIG. 8D shows the completed ablation with theablated endometrial tissue indicated at 360.

In another embodiment, the system can include an electrode arrangementin the handle 106 or within the gas inflow channel to pre-ionize theneutral gas flow before it reaches the interior chamber 152. Forexample, the gas inflow channel can be configured with axially orradially spaced apart opposing polarity electrodes configured to ionizethe gas inflow. Such electrodes would be connected in separate circuitryto an RF source. The first and second electrodes 215 (+) and 220 (−)described above would operate as described above to provide the currentthat is capacitively coupled to tissue through the walls of thedielectric structure 150. In all other respects, the system and methodwould function as described above.

Now turning to FIGS. 9 and 10, an alternate working end 122 withthin-walled dielectric structure 150 is shown. In this embodiment, thethin-walled dielectric structure 150 is similar to that of FIGS. 5 and 6except that the second polarity electrode 220′ that is exterior of theinternal chamber 152 is disposed on a surface portion 370 of thethin-walled dielectric structure 150. In this embodiment, the secondpolarity electrode 220′ comprises a thin-film conductive material, suchas gold, that is bonded to the exterior of thin-walled material 210along two lateral sides 354 of dielectric structure 150. It should beappreciated that the second polarity electrode can comprise one or moreconductive elements disposed on the exterior of wall material 210, andcan extend axially, or transversely to axis 111 and can be singular ormultiple elements. In one embodiment shown in more detail in FIG. 10,the second polarity electrode 220′ can be fixed on another lubriciouslayer 360, such as a polyimide film, for example KAPTON®. The polyimidetape extends about the lateral sides 354 of the dielectric structure 150and provides protection to the wall 210 when it is advanced from orwithdrawn into bore 120 in sleeve 110. In operation, the RF deliverymethod using the embodiment of FIGS. 9 and 10 is the same as describedabove, with RF current being capacitively coupled from the plasma 208through the wall 210 and endometrial tissue to the second polarityelectrode 220′ to cause the ablation.

FIG. 9 further shows an optional temperature sensor 390, such as athermocouple, carried at an exterior of the dielectric structure 150. Inone method of use, the control unit 135 can acquire temperature feedbacksignals from at least one temperature sensor 390 to modulate orterminate RF energy delivery, or to modulate gas flows within thesystem. In a related method of the invention, the control unit 135 canacquire temperature feedback signals from temperature sensor 240 ininterior chamber 152 (FIG. 6 to modulate or terminate RF energy deliveryor to modulate gas flows within the system.

In another aspect of the invention, FIG. 11 is a graphic representationof an algorithm utilized by the RF source 130A and RF controller 130B ofthe system to controllably apply RF energy in an endometrial ablationprocedure. In using the expandable dielectric structure 150 of theinvention to apply RF energy in an endometrial ablation procedure asdescribed above, the system is configured to allow the dielectricstructure 150 to open to different expanded dimensions depending on thesize and shape of the uterine cavity 302. The axial length of dielectricstructure 150 also can be adjusted to have a predetermined axial lengthextended outward from the introducer sleeve 110 to match a measuredlength of a uterine cavity. In any case, the actual surface area of theexpanded dielectric structure 150 within different uterine cavities willdiffer—and it would be optimal to vary total applied energy tocorrespond to the differing size uterine cavities.

FIG. 11 represents a method of the invention that automaticallydetermines relevant parameters of the tissue and the size of uterinecavity 302 to allow for selection of an energy delivery mode that iswell suited to control the total applied energy in an ablationprocedure. In embodiments, RF energy is applied at constant power for afirst time increment, and the following electrical parameters (e.g.,voltage, current, power, impedance) are measured during the applicationof energy during that first time increment. The measured electricalparameters are then used (principally, power and current, V=P/I) todetermine a constant voltage to apply to the system for a second timeinterval. The initial impedance may be also be utilized by thecontroller as a shutoff criteria for the second treatment interval aftera selected increase in impedance.

For example, in FIG. 11, it can be seen that a first step following thepositioning of the dielectric structure in the uterine cavity 302 is toapply radiofrequency energy in a first mode of predetermined constantpower, or constant RF energy (“FIRST MODE—POWER”). This first power issufficient to capacitively couple current across the dielectric tocontacted tissue, wherein empirical studies have shown the power can bein the range of 50W-300W, and in one embodiment is 80 W. This firstpower mode is applied for a predetermined interval which can be lessthan 15 seconds, 10 seconds, or 5 seconds, as examples, and is depictedin FIG. 11 as being 2 seconds. FIG. 11 shows that, in accordance withembodiments, the voltage value is determined a voltage sensor incontroller 130A and is recorded at the “one-second” time point after theinitiation of RF energy delivery. The controller includes a powersensor, voltage sensor and current sensor as is known in the art. Thisvoltage value, or another electrical parameter, may be determined andrecorded at any point during the interval, and more than one recordingmay be made, with averages taken for the multiple recordings, or themultiple recordings may be used in another way to consistently take ameasurement of an electrical value or values. FIG. 11 next illustratesthat the controller algorithm switches to a second mode (“SECONDMODE—VOLTAGE”) of applying radiofrequency energy at a selected constantvoltage, with the selected constant voltage related to the recordedvoltage (or other electrical parameter) at the “one-second” time point.In one embodiment, the selected constant voltage is equal to therecorded voltage, but other algorithms can select a constant voltagethat is greater or lesser than the recorded voltage but determined by afactor or algorithm applied to the recorded voltage. As further shown inFIG. 11, the algorithm then applies RF energy over a treatment intervalto ablate endometrial tissue. During this period, the RF energy isvaried as the measured voltage is kept constant. The treatment intervalcan have an automatic time-out after a predetermined interval of lessthat 360 seconds, 240 seconds, 180 seconds, 120 seconds or 90 seconds,as examples.

By using the initial delivery of RF energy through the dielectricstructure 150 and contacted tissue in the first, initial constant powermode, a voltage level is recorded (e.g., in the example, at one second)that directly relates to a combination of (i) the surface area of thedielectric structure, and the degree to which wall portions of thedielectric structure have been elastically stretched; (ii) the flow rateof neutral gas through the dielectric structure and (iii) the impedanceof the contacted tissue. By then selecting a constant voltage for thesecond, constant voltage mode that is directly related to the recordedvoltage from the first time interval, the length of the second,treatment interval can be the same for all different dimension uterinecavities and will result in substantially the same ablation depth, sincethe constant voltage maintained during the second interval will resultin power that drifts off to lower levels toward the end of the treatmentinterval as tissue impedance increases. As described above, thecontroller 130A also can use an impedance level or a selected increasein impedance to terminate the treatment interval.

The algorithm above provides a recorded voltage at set time point in thefirst mode of RF energy application, but another embodiment can utilizea recorded voltage parameter that can be an average voltage over ameasuring interval or the like. Also, the constant voltage in the secondmode of RF energy application can include any ramp-up or ramp-down involtage based on the recorded voltage parameter.

In general, an electrosurgical method for endometrial ablation comprisespositioning a RF ablation device in contact with endometrial tissue,applying radiofrequency energy in a first mode based on a predeterminedconstant power over a first interval, and applying radiofrequency energyin a second mode over a second interval to ablate endometrial tissue,the energy level of the second mode being based on treatment voltageparameters obtained or measured during the first interval. Power duringthe first interval is constant, and during the second period is variedto maintain voltage at a constant level. Another step in applying RFenergy in the first mode includes the step of recording a voltageparameter in the first interval, wherein the voltage parameter is atleast one of voltage at a point in time, average voltage over a timeinterval, and a change or rate of change of voltage. The second modeincludes setting the treatment voltage parameters in relation to thevoltage parameter recorded in the first interval.

Referring to FIG. 11, it can be understood that an electrosurgicalsystem for endometrial ablation comprises a radiofrequency ablationdevice coupled to an radiofrequency power supply, and control meansconnected to the radiofrequency power supply for switching theapplication of radiofrequency energy between a constant power mode and aconstant voltage mode. The control means includes an algorithm that (i)applies radiofrequency energy in the first mode (ii) records the voltagewithin a predetermined interval of the first mode, and (iii) appliesradiofrequency energy in the second mode with constant voltage relatedto the recorded voltage.

In another aspect, the invention comprises a radiofrequency powersupply, a means for coupling the radiofrequency power supply to anablation device configured for positioning in a uterine cavity, theablation device comprising a dielectric for contacting endometrialtissue, a system for recording an electrical parameter of the ablationdevice and contacted tissue, and a feedback system for varying theapplication of radiofrequency energy to tissue between a constant powermode and a constant voltage mode based on a recorded electricalparameter.

In another embodiment of the invention, FIGS. 12, 13A and 13B depictcomponents of the ablation device of FIGS. 1-2 that provide thephysician with an indication of the degree to which the dielectricstructure 150 has opened in the patient's uterine cavity 302. It can beunderstood from FIGS. 5, 6 and 8C that the spring frame 155 that movesthe dielectric structure 150 from a contracted, linear shape (FIG. 8B)to an expanded, triangular shape (FIG. 8C) results from actuating thehandle 106 to move the assembly of inner sleeve 170, intermediate sleeve115, frame 155 and dielectric structure 150 distally relative to theintroducer sleeve 110 to thus expose and deploy the dielectric structure150 in the uterine cavity 302.

Referring to FIG. 12, it can be seen that inner sleeve 170 andintermediate sleeve 115 are shown for convenience without theirrespective welded connections to spring frame elements 158 a, 158 b, 160a and 160 b. The frame elements 158 a, 158 b, 160 a and 160 b and theirspringing function can be seen in FIGS. 5 and 6. In FIG. 12, theintroducer sheath 110 is shown as being moved proximally relative to thedielectric structure 150 which corresponds to a position of thedielectric structure 150 shown in FIG. 8B. In the schematic view of FIG.12, the distal end 400 of sleeve 170 has an axial position X and can beapproximately the same axial position as the distal end 402 of theintroducer sleeve 110. It can be understood that when the dielectricstructure 150 and interior spring frame 155 are deployed in a uterinecavity, the spring force of frame 155 will tend to open the dielectricstructure 150 from a position in FIG. 8B toward the position of FIG. 8C.In FIG. 12, an initial position of the distal end 405 of sleeve 170 hasan axial position indicated at A which corresponds to plan shape A′ ofthe dielectric structure 150. In a typical procedure, the spring forceof frame 155 will move the distal end 405 of sleeve 170 toward an axialposition B which corresponds to expanded dielectric plan shape B′ ortoward an axial position C and corresponding expanded dielectric planshape C′. Dielectric plan C′ represents a fully expanded dielectricstructure 150. In order to allow the spring force of frame 155 to expandthe frame and dielectric structure 150, the physician may gently andvery slightly rotate, tilt and translate the expanding dielectricstructure 150 in the uterine cavity 302. After thus deploying thedielectric structure, the different dimensions of uterine cavities willimpinge on the degree of expansion of the dielectric structure 150—andthe size and surface area of the dielectric structure, as an example,will be within the dimension range between plan shapes A′ and plan shapeC′ of FIG. 12.

In one aspect of the invention, it is important for the system andphysician to understand the degree to which the dielectric structure 150and frame 155 has expanded in the uterine cavity. If the dielectricstructure 155 has not expanded to a significant degree, it may indicatethat the uterine cavity is very small or very narrow, that fibroids areimpinging on dielectric structure preventing its expansion, that theuterine cavity is very asymmetric, or that a tip of the dielectricstructure and frame 155 has penetrated into an endometrial layer,perforated the uterine wall or followed a dissection path created by asounding procedure just prior to deployment of the dielectric structure.Further, in one system embodiment, the dielectric structure 150 ispreferred to have a minimum surface area directly related to itsexpanded shape to thus cooperate with an RF energy delivery algorithm.

In one embodiment, the system provides a “degree of frame-open”signaling mechanism for signaling the physician that the frame 155 anddielectric structure 150 has expanded to a minimum predeterminedconfiguration. The signaling mechanism is based on the relative axiallocation of inner sleeve 170 and sleeve 115 as can be understood fromFIGS. 12 and 13A-13B. In FIGS. 1 and 2, it can be seen that a slidingelement 450 is exposed in a top portion of handle component 114B toslide axially in a slot 452. In a schematic view of handle component 114b in FIGS. 13A-13B, it can be seen that the proximal end 454 of sleeve115 is fixed in handle component 114 b. Further, the proximal end of 456of the inner sleeve 170 is connected to the sliding element 450 thatslides in slot 452. Thus, it can be understood that inner sleeve 170 isslidable and free-floating in the bore 175 of sleeve 115 and can bemoved axially to and fro depending to the opening spring force of frame155—which force can be constrained by the frame being withdrawn into thebore 120 of introducer sleeve 110 or by uterine walls impinging on thedielectric structure 150 and frame 155 when deployed in a uterinecavity. As can be seen in FIGS. 1, 2, 13A and 13B, the sliding elementhas at least two axially-extending indicators 460A and 460B that can bedifferent colors that slide axially relative to status-indicating arrowelement 465 in a fixed location in the handle 114 b. In one embodiment,indicator 460A can be red for “stop” and indicator 460B can be “green”,for indicating whether to stop proceeding with the procedure, or to goahead with the ablation procedure. In FIG. 13A, it can be seen thatinner sleeve 170 and its distal end 405 are only axially extended atpoint A which corresponds to dielectric expansion profile A′. Thelimited expansion of dielectric structure at profile A′ is indicated atthe slider 450 wherein the arrow 465 points to the red ‘stop” indicator460A which indicates to the physician to stop and not proceed with theablation procedure due to limited expansion of dielectric structure 150.

FIG. 13B depicts an extension of inner sleeve 170 and its distal end 405to axially extended at point B which corresponds to dielectric expansionprofile B′. This intermediate expansion of dielectric structure 150 atprofile B′ is indicated to the physician by observing slider 450 whereinarrow 465 points to the green indicator 460B which indicates “go”—thatis, the physician can proceed with the ablation procedure since thedielectric structure 150 and frame 155 have expanded to a predetermineddegree that cooperates with an RF energy delivery algorithm. It can beunderstood from FIG. 13B that sleeve 170 can move axially towardextended position C with corresponding dielectric structure profile C′and indicator arrow 465 will again point to the “go” portion 460B ofsliding element which is green.

In another aspect of the invention also depicted in FIGS. 13A-13B, thehandle component 114 b can include a electrical contact sensor 470 thatdetects the axial movement of sliding element 450 and sleeve 170relative to sleeve 115 to thereby provide an electronic signalindicating the degree of expansion of the frame 155 and dielectricstructure 150. In one embodiment, the electronic signal communicateswith RF controller 130B to disable the system if the relative axialpositions of sleeves 170 and 115 do not indicate a predetermined degreeof expansion of the frame 155 and dielectric structure. The system canfurther include an override mechanism, whereby the physician canmanipulate the instrument slightly back and forth and rotationally toevaluate whether the frame 155 opens incrementally more. In anotherembodiment, the electrical sensor 470 can detect a plurality of degreesof expansion of the frame 155 and dielectric structure 150, for exampleas depicted by an electrical contact be activated at positions AA, BB,CC, and DD of the slider 450 in FIGS. 13A-13B, wherein each degree ofexpansion of frame 155 signals the controller to select a different RFdelivery algorithm. The various different RF delivery algorithms canalter at least one of: (i) the duration of a treatment interval, forexample from between 60 seconds and 240 seconds, (ii) the relationbetween a recorded voltage and a treatment voltage as described in thetext accompanying FIG. 11 above (e.g., the treatment voltage can equalthe recorded voltage, or vary as a factor about 0.8, 0.9, 1.0, 1.1 or1.2 times the recorded voltage; (iv) can vary a ramp-up or ramp-down involtage, or can a time interval of the first and second modes of RFenergy delivery described above. The number of degrees of expansion offrame 155 and dielectric structure can range from 1 to 10 or more.

The embodiment of FIGS. 1, 2, 13A and 13B depict indicator subsystemsthat include visual and electrical signals, but it should be appreciatedthat the indicator subsystem can provide any single or combinationsignals that can be visual, aural or tactile with respect to theoperator and/or electrically communicate with microprocessors,programmable logic devices or controllers of the ablation system.

In another embodiment of the invention, FIGS. 14-16B illustrate anothersystem embodiment 500 that is similar to previous embodiments exceptthat another cervical sealing structure or element is shown. FIG. 14shows a cervical seal 505 carried by a distal portion of the introducersleeve assembly 510 that extends along longitudinal axis 512. Theelongated cervical seal 505 comprises a flexible material with anannular thin wall 515 formed with a plurality of annular ridges orundulations 516 spaced apart by annular recesses 518. The annular ridgesprovide a bellows-like form. The seal 505 can be fabricated of abiocompatible elastomeric material such as silicone. The elastomericmaterial also can have reinforcing braids or woven material therein, orcan have metal spring wire material therein. The sleeve assembly 510comprises concentric polymer or metal sleeves as shown in FIG. 14,15A-15B including first outer sleeve 520A and inner sleeve 520B. A boreor passageway 525 in the inner sleeve 520B is configured for carryingand deploying an ablating dielectric structure 150 as depicted in FIG.9. The elongated cervical seal 505 has proximal end 530 a and distal end530 b. In FIGS. 14 and 15A-15B, it can be seen that proximal end 530 aof seal 505 is bonded to a distal region 532 a of outer sleeve 520A anddistal end 530 b of seal 505 is bonded to a distal region 532 b of innersleeve 520B. The sealing element or seal 505 is coupled to the sleeves520A and 520B by bonds indicated at 536 which can comprise any suitableadhesive, glue, ultrasonic bonding or the like.

In FIGS. 15A-15B, it can be understood that axial movement of sleeve520B relative to sleeve 520A can axially compress or axially extend theseal 505. In one embodiment, the seal 505 is a molded material having arepose form shown in FIG. 15A with a plurality of annular ridges 516 andannular recesses 518 with the height AA of the ridges ranging from about1 mm to 6 mm around the sleeve assembly 510 which has an outer diameterranging from about 3 mm to 8 mm. The annular ridges 516 can have a widthof 0.5 to 5 mm and similarly the annular recesses 518 can have a widthof 0.5 to 5 mm. The annular ridges and recesses can have similar ordissimilar widths, and such widths can vary over the axial length of theseal. The thickness of the thin wall material can range from 0.001″ to0.1″. The length BB of the seal 505 (FIG. 15A) in its repose state canbe at least 2 cm, 4 cm or 6 cm. A finger grip 540 is coupled to aproximal end 542 of the outer sleeve 520A that can be used to move theouter sleeve 520A relative to the inner sleeve 520B.

In one embodiment, still referring to FIGS. 14 and 15A, it has beenfound useful that the distal region of seal 505 has ridges 516 having agreater height AA for engaging and sealing around the internal cervicalos 320 and a lesser height of ridges 516 for the seal portion thatextends through the cervical canal. In the embodiment of seal 505 shownin FIGS. 14 and 15A, the exterior profile of the seal's repose state hasa distal portion 544 a with a first outermost diameter and a proximalportion with a second lesser diameter, but it should be appreciated thatthe external profile of the seal 505 can be tapered in the proximaldirection or can have a plurality of tapers along the overall length BBof the seal.

In a method of use, it has been found that an elongate seal 505 with aplurality of annular ridges 516 of an elastomeric material inserted intoa cervical canal creates an effective seal since the ridges can deformindependently to accommodate any shape and dimension of cervical canal.In FIG. 15A, it can be understood that the seal 505 is molded havinglength B, but can be axially compressed to a shorter axial length forsealing a cervical canal. For insertion into a cervical canal, the seal505 can be axially stretched as shown in FIG. 15B to have an outsidediameter similar to the diameter of the sleeve assembly 510. FIG. 15Bshows that the seal 505 when axially stretched has the annular regions516 and 518 pre-disposed to fold or deploy into the ridges, but itshould be appreciated that the seal 505 can be stretched so that theseal is without undulations until the stretched seal is tight againstthe outer sleeve 520A. The sleeve assembly 510 can have a lock andrelease mechanism in grip 540 to lock the seal 505 in an extendedposition in preparation of insertion into a patient's cervical canal. Inthe embodiment of FIG. 15A, it can be seen that grip 540 has a buttonmechanism 545 that can press against inner sleeve 520B to lock thesleeves in a selected axial relationship. The lock and release mechanismcan have an element that engages the inner sleeve 520B or can deform theouter sleeve 520A to prevent its slippage relative to the inner sleeve.

FIGS. 16A and 16B illustrate a method of using the system embodiment 500of FIG. 14 in accessing a patient's uterine cavity 302 and sealing thecervical canal 314, which is useful for performing a uterine cavityintegrity check and for prevented heated fluids from migrating into thecervical canal during an endometrial ablation procedure. FIG. 16Aillustrates a first step of the method in which the elastomeric seal 505is axially extended or stretched by moving the sleeve assembly as shownin FIG. 15B, and thereafter the assembly is inserted into the cervicalcanal. It should be appreciated that the seal 505 and sleeve assemblyalso can be inserted into the cervical canal without stretching theseal, and the step of pushing the assembly distally through the outercervical os 312 would cause the seal to stretch and allow it passagethrough the cervical canal. FIG. 16B illustrates a subsequent step ofthe method wherein the physician actuates the outer sleeve 520A movingit distally relative to inner sleeve 520B to axially compress the sealwhich results in the seal assuming the expanded cross-section form withcorrugated surfaces wherein the ridges 516 contact tissue about thecervical canal 314.

Still referring to FIG. 16B, the physician can introduce an ablatingdielectric structure 150 through passageway 525 in the sleeve assemblyand open the frame of the ablation working end 122 (phantom) view,either before or after the seal 505 is deployed and expanded in thecervical canal. After the seal 505 is deployed as shown in FIG. 16B, theuterine cavity can be characterized as non-perforated or perforated asdescribed above, and the ablation system can be actuated as describedabove. Upon completion of an endometrial ablation procedure, the seal505 can be moved the position of FIG. 16A, the dilectric structure 150is collapsed and withdrawn into passageway 525 and the sleeve assembly510 and dielctric structure 150 can be withdrawn from the patient'scervical canal.

FIG. 17 illustrates another embodiment of cervical sealing structure 605or seal which is similar to previous embodiments. The seal 605 of FIG.17 again is carried by a distal portion of the introducer sleeveassembly 510 that extends along longitudinal axis 512. The elongatedcervical seal 605 comprises a thin wall silicone or similar elastomericwith an elongated helical ridge region 610. The seal 605 is configuredfor axial deformation as described in the previous embodiment between afirst transversely expanded shape for engaging a cervical canal and asecond transversely non-expanded shape for trans-cervical insertion. InFIG. 17, the seal is depicted in its repose shape and can be stretchedto reduce its transverse section for introducing into a cervical canal.The seal 605 of FIG. 17 has a distal region 615 of annular ribs 618 asdescribed in the previous embodiment, but such ribs 618 also could havea helical configuration.

FIGS. 17-18 further show that an interior chamber 620 at the interiorthin wall material 622 which can expand or inflate the helical ridge 625when pressurized with fluid that is in communication with an inflationsource 630. The inflation fluid can be provided by any gas or liquidsource, such as a syringe filled with air, CO₂ or another biocompatiblegas. In one embodiment, the inflation source 630 is fluidly coupled to alumen 632 is the wall of seal as shown in FIGS. 17-18. Thus, the seal605 can be configured with a first maximum expanded transverse dimensionAA (FIGS. 17-18) by the relative axial position of the sleeves asdescribed above. Further, the seal 605 can be configured with at least asecond greater expanded transverse dimension BB (FIGS. 17-18) whichresults from pressurizing the interior chamber 620 which effectivelystretches or bulges the helical ridges 625 to an expanded shape 625′.

FIG. 19 illustrates another embodiment which functions similar to thatof FIG. 17, except that a fluid inflow source 640 is coupled to lumen632 to provide a continuous flow of gas or liquid through the interiorchamber which can exit another lumen 642 in sleeve assembly 510. Theinflow source 640 can pressurize and expand the ridges 625 of the sealand a restrictor valve 645 can control outflows to thus expand the sealand provide a fluid flow through the seal 605 for cooling the sealassembly.

FIG. 20 shows another embodiment in cut-away view wherein the seal 605′includes means for causing the ridges 625 to expand while the valleys648 of the seal are resistant to radial expansion. In one embodiment,the helical valley 648 is overmolded with a higher durometer material650 that allows for axial compression of the seal but resists radialinflation. In another embodiment, the helical valley 648 can beconfigured with a much thicker elastomer than the ridges 625, to preventradial expansion of the valleys. In another embodiment, the helicalvalley 648 can include an embedded helical spring element.

FIG. 21 illustrates a seal and sleeve assembly 700 that carries anelongate cervical seal 705 and distal balloon portion 708 which canfunction as previously described embodiments of FIGS. 17-20. In theembodiment of FIG. 21, the entire sleeve assembly 700 is independent ofthe shaft 110 of a probe slidably received within a central passage ofthe sleeve assembly, such as an ablation probe similar to that of FIGS.1-2. In other words, the seal assembly can be actuated to expand thedistal balloon 708 and deploy the cervical seal 705 independent of theaxial position of the shaft 110 of the ablation device, thus providingall of the advantages described previously.

More particularly, balloon 708 and the distal end 710 of the elongatecervical seal 705 are sealably coupled to sleeve 715 which extendsthrough the entire assembly 700 from proximal sleeve portion 716 a todistal sleeve portion 716 b. The sleeve 715 has a bore 718 (centralpassage) therein that slidably accommodates the probe shaft indicated at110. The proximal end 719 of the cervical seal 705 is coupled toslidable collar member 720 which is configured to slide over sleeve 715to thus move the seal 705 from an axially-extended position toward anon-extended position to thereby engage the wall of the endocerivcalcanal. The collar 720 will remain accessible to the treating physicianto allow insertion and removal of the sleeve assembly 700 as well asoptionally locking and unlocking the probe shaft 110 within the sleeveassembly. The collar member 720 includes an 0-ring 724 or other type ofsliding gasket or seal that interfaces with sleeve 715 to maintain fluidpressure and inflation in the cervical seal 705 and distal balloon 708.Inflation source 630 as described previously can be used to inflatecervical seal 705 and balloon portion 708. The inflation source 630 canbe a syringe that injects any suitable fluid, such as air, CO₂, water orthe like. In the embodiment of FIG. 21, the inflation source can becoupled by flexible tubing to an inflation port indicated at 732,wherein the fluid inflow expands both the cervical seal 705 and thedistal balloon 708. In another embodiment, the cervical seal 705 anddistal balloon 708 can be inflated sequentially by separate inflows froman inflation source 630.

FIG. 21 also illustrates an optional locking mechanism (such as button735) in the collar 720 that can be selectively actuated to lock andunlock the collar 720 in a selected axial position relative to sleeve715 and probe shaft 110 within the sleeve 715. The locking mechanism canbe any suitable spring-loaded element that pushes on, and thus grips andcollapses the slightly flexible inner sleeve 715 which will impinge onprobe shaft 110. The button 735 and locking mechanism can be pushedinwardly to unlock the locking mechanism or vice versa. The lockingmechanism allows the physician to lock and stabilize the probe shaft 110within the sleeve assembly during or after a therapeutic or diagnosticprocedure or can be used with any other toolshaft that has beenpositioned within the uterus.

FIG. 21 further illustrates that the cervical seal 705 has a helical,undulating surface with ridges 736 and troughs 738. The seal 705 can bemolded of a silicone or any other similar complaint material with theridges and trough, with a helical constraining element 704 molded intothe trough regions. The constraining element 740 can comprise anynon-stretch polymer such Kevlar or the element 740 can be a metal wire.In use, inflation of the cervical seal will tend to bulge outwardly theridges 736 of the seal to engage the cervical canal tissue.

FIGS. 22A-22B illustrate the method of using the cervical seal assembly700 of FIG. 21 in preparation for an endometrial ablation procedure.FIG. 22A depicts an initial step of inserting the seal assembly 700through the patient's endocervical canal with the cervical seal 705 anddistal balloon 708 in a non-expanded condition, either independent of ortogether with the probe shaft 110. FIG. 22B next illustrates the stepsof moving the collar member 720 axially over sleeve 715 and alsointroducing an inflation medium from inflation source 630 to therebyexpand both the distal balloon 708 and cervical seal 705 to seal theuterine cavity. After positioning the seal assembly 700 to seal theuterine cavity as shown in FIG. 22B, the probe shaft 110 can beintroduced to any suitable depth in the uterine cavity to thereafterdeploy the working end of an ablation probe, such as the working end ofFIG. 2 or FIG. 9.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

1. A system for transcervical introduction to a patient's uterus, saidsystem comprising: a radially expandable sleeve having a proximal end, adistal end, and a central passage therebetween, said sleeve beingadapted to be introduced into the cervix in a reduced widthconfiguration and to be immobilized in the cervix in an expanded widthconfiguration; and a probe shaft slidably received in the centralpassage of the sleeve, wherein the probe shaft may be advanced andretracted within the central passage while the sleeve remainsimmobilized in the cervix.
 2. A system as in claim 1, wherein the sleevecomprises a proximal collar with a locking mechanism that selectivelylocks the sleeve to the probe shaft.
 3. A system as in claim 2, whereinthe locking mechanism comprises a button on the collar which can bepushed inwardly to engage and lock the probe shaft.
 4. A system as inclaim 1, wherein the sleeve comprises a distal balloon which can beinflated to engage an interior surface of a cervical os.
 5. A system asin claim 1, wherein the sleeve comprises a tubular assembly and adeformable thin-walled seal disposed over the tubular assembly, the sealconfigured for axial deformation between a first transversely expandedshape for engaging a cervical canal and a second transverselynon-expanded shape for trans-cervical insertion.
 6. A system as in claim5, wherein the proximal and distal ends of the seal are coupled to firstand second concentric tubes, respectively, wherein relative axiallymovement of the sleeves provides said axial deformation.
 7. A system asin claim 5, wherein the seal comprises an elastomeric material.
 8. Asystem as in claim 5, wherein the seal comprises a thin wall silicone.9. A system as in claim 5, wherein the seal is formed with helical ridgeand valley regions for folding and unfolding upon said axialdeformation.
 10. A system as in claim 5, further comprising apressurized fluid source connected to selectively inflate the deformablethin-walled seal when said seal is in its transversely expanded shape.11. A system as in claim 10, wherein the deformable thin-walled seal hasannular or helical first and second regions of first and seconddurometers, respectively, with the first region having a higherdurometer than the second region; and wherein the pressurized fluidsource is configured to apply pressurized fluid to the seal to expandthe second region, but not the first region, in accordance with therespective durometers of the regions.
 12. A system as in claim 5,wherein the deformable thin-walled seal has a stretched cross-sectionfor trans-cervical insertion and a non-stretched cross-section forsealing the cervical canal, wherein the seal contains a fluid-tightinterior chamber having a wall with annular or helical regionsconfigured for differential transverse expansion upon inflation; and apressurized fluid source being configured to apply pressurized fluid tothe seal to differentially expand the annular or helical regions.
 13. Amethod for accessing a patient's uterus, said method comprising:immobilizing a sleeve in the patient's cervix, said sleeve having acentral passage; and repositioning a probe shaft within the centralpassage of the sleeve while the sleeve remains immobilized.
 14. A methodas in claim 13, wherein the sleeve is immobilized with the probe presentin the central passage.
 15. A method as in claim 13, wherein the sleeveis immobilized without the probe in the central passage, furthercomprising advancing the probe through the central passage after thesleeve has been immobilized.
 16. A method as in claim 13, wherein thesleeve is immobilized by radially expanding the sleeve within thecervix.
 17. A method as in claim 16, wherein the sleeve is radiallyexpanded allowing or causing the sleeve to axially foreshorten.
 18. Amethod as in claim 16, wherein the sleeve is radially expanded byinflating a wall of the sleeve.
 19. A method as in claim 18, wherein adistal balloon is inflated on the wall.
 20. A method as in claim 16,wherein the sleeve is radially expanded by both allowing or causing thesleeve to axially foreshorten and by inflating a wall of the sleeve. 21.A method as in claim 13, further comprising locking the sleeve onto theprobe shaft.
 22. A method as in claim 21, wherein locking comprisesactuating a locking mechanism on a proximal collar on the sleeve.